1. Field of the Invention
This invention resides in the field of polyacrylamide electrophoresis and the polyacrylamide gels used in the electrophoresis.
2. Description of the Prior Art
The wide use of polyacrylamide gel electrophoresis (PAGE) in research and diagnostics, and in biochemistry laboratories in general, is due in large part to the optical transparency and electrical neutrality of polyacrylamide gels, and to the flexibility and adaptability of polyacrylamide gels to a wide range of molecular sizes of the species to be separated in the gel. This flexibility arises from the manufacturer's ability to control the porosity of the gel by varying the concentration of the acrylamide monomer and the proportion of the bis-acrylamide crosslinking agent relative to the monomer. PAGE is particularly useful for protein separations conducted in the presence of sodium dodecyl sulfate (SDS), either incorporated into the gel or included in the running buffer. Commonly used buffers are tris(hydroxymethyl)-aminomethane (“Tris”) and bis(2-hydroxyethyl)amino-tris(hydroxymethyl)methane (“Bis-Tris”). Prominent among polyacrylamide gels for protein separations is one originally described by Laemmli, U.K., Nature 227: 680 (1970), and which contains Tris-HCl as a buffer at pH 8.8. Unfortunately, gels with pH values this high tend to hydrolyze over time, even when the gels are refrigerated. Hydrolysis reduces the migration distance of individual proteins within the gels and lowers the resolution of the protein bands. If the pH is lowered in an attempt to avert hydrolysis, a certain degree of sharpness in the resolution of separated proteins in the gel is lost, and the ability to obtain useful analyses of protein mixtures is often lost as well.
One means of overcoming this problem is the inclusion of triethanolamine in the gel, as disclosed in commonly owned co-pending U.S. patent application Ser. No. 12/552,104, filed Sep. 1, 2009. The present invention provides another means.